<template>
       <div class="s-canvas">
           <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
       </div>
</template>
<script>
  export default {
       name: 'SIdentify',
       data(){
           return{
               
           }
       },
       props: {
          identifyCode: {
              type: String,
              default: '1234'
          },
          fontSizeMin: {
              type: Number,
              default: 25
          },
          fontSizeMax: {
              type: Number,
              default: 30
          },
          backgroundColorMin: {
              type: Number,
              default: 255
          },
          backgroundColorMax: {
              type: Number,
             default: 255
          },
          colorMin: {
              type: Number,
              default: 0
          },
          colorMax: {
             type: Number,
              default: 160
          },
          lineColorMin: {
              type: Number,
              default: 100
          },
          lineColorMax: {
              type: Number,
              default: 255
          },
          dotColorMin: {
              type: Number,
              default: 0
          },
          dotColorMax: {
              type: Number,
              default: 255
          },
          contentWidth: {
              type: Number,
              default: 130
          },
          contentHeight: {
              type: Number,
              default: 42
          }
      },
      methods: {
          // 生成一个随机数
        randomNum(min, max) {
            return Math.floor(Math.random() * (max - min) + min)
        },
        // 生成一个随机的颜色
        randomColor(min, max) {
            let r = this.randomNum(min, max)
            let g = this.randomNum(min, max)
            let b = this.randomNum(min, max)
            return 'rgb(' + r + ',' + g + ',' + b + ')'
        },
        drawPic() {
            let canvas = document.getElementById('s-canvas')
            let ctx = canvas.getContext('2d')
            ctx.textBaseline = 'bottom'
            // 绘制背景
            ctx.fillStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax)
            ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
            // 绘制文字
            for (let i = 0; i < this.identifyCode.length; i++) {
                this.drawText(ctx, this.identifyCode[i], i)
            }
            this.drawLine(ctx)
            this.drawDot(ctx)
        },
        drawText(ctx, txt, i) {
            ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax)
            ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei'
            let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
            let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
            var deg = this.randomNum(-45, 45)
            // 修改坐标原点和旋转角度
            ctx.translate(x, y)
            ctx.rotate(deg * Math.PI / 180)
            ctx.fillText(txt, 0, 0)
            // 恢复坐标原点和旋转角度
            ctx.rotate(-deg * Math.PI / 180)
            ctx.translate(-x, -y)
         },
        drawLine(ctx) {
             // 绘制干扰线
             for (let i = 0; i < 5; i++) {
                ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax)
                ctx.beginPath()
                ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
                ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight))
                ctx.stroke()
            }
        },
        drawDot(ctx) {
            // 绘制干扰点
             for (let i = 0; i < 80; i++) {
                ctx.fillStyle = this.randomColor(0, 255)
                ctx.beginPath()
                ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI)
                ctx.fill()
            }
        }
     },
     watch: {
         identifyCode() {
            this.drawPic()
         }
     },
     mounted() {
         this.drawPic()
     }
 }
</script>
<style scoped>
 .s-canvas {
     height: px;
    
 }
 .s-canvas canvas{
     margin-top: 1px;
     margin-left: 8px;
 }
</style>